1. Field of the Invention
The present invention relates to polypeptides having mutanase activity and isolated nucleic acid sequences encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the nucleic acid sequences as well as methods for producing the polypeptides. The invention further relates to compositions comprising the polypeptides and methods of use thereof.
2. Description of the Related Art
The formation of dental plaque leads to dental caries, gingival inflammation, periodontal disease, and eventually tooth loss. Dental plaque is a mixture of bacteria, epithelial cells, leukocytes, macrophages, and other oral exudate. The bacteria produce glucans and levans from sucrose found in the oral cavity. These glucans, levans, and microorganisms form an adhesive matrix for the continued proliferation of plaque.
Streptococcus mutans is a common bacterium associated with dental plaque. Extracellular insoluble polysaccharides produced by this bacterium in the oral cavity play an important role for adhesion and proliferation of bacteria on the surface of teeth and, hence, may be important in the etiology of dental caries. Mutan is the major component of the insoluble polysaccharides produced by Streptococcus mutans and is comprised of a backbone with .alpha.-1,3-glycosidic linkages and branches with .alpha.-1,6-glycosidic linkages.
Mutanases are .alpha.-1,3-glucanases (also known as .alpha.-1,3-glucanohydrolases) which degrade the .alpha.-1,3-glycosidic linkages in mutan. Mutanases have been described from two species of Trichoderma (Hasegawa et al., 1969, Journal of Biological Chemistry 244:5460-5470; Guggenheim and Haller, 1972, Journal of Dental Research 51:394-402) and from a strain of Streptomyces (Takehara et al., 1981, Journal of Bacteriology 145:729-735). A mutanase gene from Trichoderma harzianum has been cloned and sequenced (Japanese Patent No. 4-58889/A).
Although mutanases have commercial potential for use as an antiplaque agent in dental applications and personal care products, e.g., toothpaste, chewing gum, or other oral and dental care products, the art has been unable to produce mutanases in significant quantities to be commercially useful.
It is an object of the present invention to provide new mutanases which can be produced in commercially useful quantities.